This invention relates to gas barbecue grills for outdoor use. More particularly, this invention relates to gas barbecue grills in which liquified petroleum gas is supplied under pressure to a duct in which gas and air are intermixed, the mixture then flowing into a plenum chamber in which the gas and air are more thoroughly mixed, the mixture then flowing upward through a multiplicity of holes in a burner plate to burn at the surface of that plate, creating heat and infrared radiation for cooking food placed on a grid located above the burner plate.
Conventional gas barbecue grills typically comprise a box-like shell having a bottom, four sides, and an open top, to which is attached a cover. Across the open top is a grid for supporting food to be cooked. Below the grid is a grate on which refractory briquettes are placed. Below the briquettes are one or more metal gas burners, having a plurality of small holes, to which gas and air are fed through a venturi. The gas is typically supplied to the venturi at a pressure of between about 4 inches and about 11 inches of water. Also typically, the gas is supplied from a high pressure cylinder of liquid petroleum gas, through a pressure regulator which reduces the gas pressure to that desired. The burning gas-air mixture heats the briquettes, and combustion products pass upward through the grid supporting the food. The purposes of the briquettes are to distribute the heat evenly across the underside of the grid, to insulate the gas flames from interference by wind, and to provide a surface on which liquids from cooking foods can be vaporized to enhance the flavor of the foods.
Another type of conventional gas barbecue grill incorporates perforated refractory burner elements. Pressurized gas is supplied through venturis to plenum chambers together with air to form a combustible mixture which passes through holes in the refractory and is ignited and burns on the outer surface of the burner elements. The elements are heated sufficiently to emit convective and infrared radiation.
One problem with both types of conventional barbecues is their susceptibility to wind currents. Drafts tend to extinguish the flames, and consequently cumbersome baffling and other means are required to protect the burners. Another problem, particularly prevelant in barbecues using perforated refractories, is heat distribution. Heat is not distributed uniformly over the food cooking surface. A third problem, also particularly prevalent in barbecues using perforated refractories, is flashback-combusion below the burner surface. A fourth problem in conventional barbecue grills is the difficulty in cleaning them. Food and liquids drip into the grill container and accumulate in the bottom. No convenient means is provided to remove the parts of the barbecue grill or to access the inside bottom of the container.